Resonant Current Steps in Josephson Structures with a Layer from a Material with Strong Spin–Orbit Interaction

Abstract

The microwave and magnetic parameters of Josephson Nb/Au/Sr₂IrO₄/YBa₂Cu₃O_x mesastructures with a layer of Sr₂IrO₄, a material representing a Mott antiferromagnetic insulator with a high spin–orbit interaction energy E_SO ~ 0.4 eV, were studied. Shapiro steps, oscillating with radiation power, appeared under monochromatic electromagnetic radiation confirm the Josephson properties of these structures. In the presence of a weak magnetic field H < 15 Oe, the voltage–current characteristics (VCCs) had resonant current steps at voltages V_n, which were inversely proportional to the size L of structures in plane. Polarity reversal in the electrical current I led to asymmetry in the arrangement of resonant current steps. At a specified magnetic field H, the voltage V_n remained constant, and the amplitudes of resonant current steps nonmonotonically changed.